In reality, if you don't have thousands and thousands of Onion with a staking weight in the 100,000's, I honestly don't think ever. For an optimistic guess, maybe 3 years, based on the network weight also always increasing? I'm not the best one to ask, but you've got to recalibrate your expectations .
I love DO for it's potential future utility and have held DO -in a similar weight range- for weeks and weeks and have never staked. Not the end of the world.
i don't own thousands of onions and my weight was 6000 and i staked twice so i think its more a matter of luck also